, an essential amino acid, vegetarian diets may provide little, pure usp grade material, the grade used for clinical nutrition not animal feed! vegetarian friendly tablets & a relevant dose, manufactured to gmp pharmaceutical standardslysine is termed an essential amino acid as it is one of the eight amino acids that our bodies can not make & so we are completely reliant on our diets to provide lysine. we require 2-3 g a day of lysine & it is most abundant in animal based foodstuffs such as meat. there is very little lysine in most vegetables & even vegetable proteins are not particularly high in lysine & so some experts believe that vegetarian & vegan diets may provide rather low levels of lysine. huge quantities of lysine are used in agriculture as it is the only amino acid that is routinely added to animal feeds. however we use a grade called usp meaning its quality & purity makes it suitable for clinical nutrition products. very cheap lysine products may be based on the lower grade less purified animal feed grade.